Antislipping tread.



' No. 924,994. PATBNTED JULY s, 1999.

' H. F. LIVERMORE.

ANTISLIPPING TREAD.

APPLICATION FILED JULY 28, 1905.

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HOMER F. LIVERMORE, OF BROOKLINE, MASSACHUSETTS.

ANTISLIPPING TREAD. p

Specification of Letters Patent.

Patented July 3, 1906.

Application filed July 28, 1905. vSerial No. 271.660.

27o all whom it moby concern:

Be it known that I, HOMER F. LIVERMORE, a citizen of the United States, and a resident of Brookline, in the county of Norfolk, Commonwealth of Massachusetts, have made certain new and useful Improvements in Antisli ping Treads, of which the following is a fufl), clear, and exact description.

This invention relates to a type of tread wherein a comparatively hard plate is formed with circular :openings filled with lugs of lead or other` antislipping materia This type of tread is usually of malleable cast-iron, with the rims of said openings raised above the remaining surface of the plate in order to permit of considerable wear of the antislippin plugs before the said surface is reached.

' T e obj ect of my invention is the construction of a tread of this general type in which said raised rims shall be made so hard and wear-resistant as to protect for a largely-increased length of time the soft lead within them and so prolong the life of the treads, for I have discovered that the lead plugs can be protectedI quitev largely by the rims surrounding thein without diminishing the antislipping function thereof. In accomplishing this I make the tread-plates from sheet-steel, stamping up the opening rims andhardening them by the combined operations o'f drawing and compressing. Referring to the drawings forming part of this specification, Figure 1 is a plan view, on an enlarged scale, of a portion of a tread made in accordance with my invention. Fig. 2 is a sectional View through one of said rims and lugs. Fig. 3 is a sectionalview showing t e formation of one of said rims, and Fig. 4 is a similar viewshowing the compression portion of the process.

The numeral 1 designates the tread-plate; 2, the raised rims surroundin the circular openings 3,1within which the ead plugs 10 In forming a tread a sheet of low-grad( steel of proper thickness, width, and lengtfhas punched therein a number of small holes withdrawal of the lead plug after the latter l has been introduced within the opening 3 and l therein, the upper part of each of which is equal to the desired outer diameter of the rim flanges 2, while the depth of the shoul` der 22 thereof equals the proposed height of said flanges. One of said small holes in the plate 1 being located directly over an opening 21 in the die, the tool or punch 25 is forced downward until the ed e surrounding said small hole is brought Yto t e form shown in Fig. 3, but not uite reaching the shoulder 22. 'This tool is t en withdrawn rand a tool 26 forced downward into the opening made by the former, its diameter beinglar er and its nose being cut square across. T 's second tool acts to depress the rim 2 into contact with the shoulder 22 and to'compress between the tool end and said shoulder as an anvil the metal composing the extreme portion of said rim or flange. Said tool 2 6 is enabled to thus' compress said rim 4by its enagement with the internal shoulder 4,

ormed during` the earlier `portion of said tools descent'. By thus strongly compressing the fibers of the steel composing the outer part of each rim or flange the latter is largely increased in hardness and wearing ability. I also find that the earlier step of forcing the metal into the flange form shown in Fig. 3 acts to harden the same, owing to theperipheral elongation given to the outer part of said rim or flange andthe consequent radial compression in the same manner that wire is hardened by its elongationand compression in being1 drawn. Another function performed e internal shoulder 4 is to prevent the then compressed., as shown in Fig. 2.

What claim as my invention, and for which I desire Letters Patent,V is as follows, to wit:

1. Atread comprisingla sheet-metal plate having openings t roug it each surrounded with an upstanding rim terminally compressed, and antislipp'ing plugs inserted in said openings and rims. y

2. The' tread comprising a sheet-metal plate havin openings through it each surrounded wit .an upstanding rim terminally compressed and hardened; and antislipping plugs inserte/d in said openings and rims.

. 3. The tread composed of a sheet-metal IOO plate having openings vthrough it each sur; vention lI have hereunto set my hand this rounded with a rim or ange, and antislip- 21st day ofJuly, 1905.

ping plugs inserted in said openings and rims n HOMER F LIVERMORE or flanges; said sheet metal being 10W-grade" i 5 steel, and said rims or flanges being termi- Witnesses:

y nelly hardened., A. B.v UPHAM, i In testimony that 1 Claim the foregoing in- F. H. WUEsT. 

